Within the dentistry field there is the special area of Endodontics which deals with restoring teeth which have "died" from bacteria that have reached the nerve pulp within the tooth. Most frequently the infecting bacteria have reached the pulp and the nerve of the tooth through cavities in the crown of the tooth. If allowed to go untreated infection will reach the membrane surrounding the root of the tooth, as well as the adjacent bone. If the infection centers around the apex or end of the root, it may become a periapical lesion.
With the best endodontic treatment, a recently absessed tooth may take many weeks to heal in the bone area. After the dead nerve and pulp of the tooth have been removed and the root canal reamed out by very small hand manipulated reamers. (of the order of 0.005 to 0.040 of an inch diameter) the extirpated root canal may then be plugged and sealed at the crown.
If the pulp infection bas progressed too far to where a lesion can be observed around the apex of the infected root canal, the Dentist may prescribe large doses of antibiotic to help the healing process. However, even when treated with the antibiotic, the lesions may not readily respond and can persist for as long as two years, before completing the healing. This is because so little of the antibiotic can reach the infected area of the bone, because of the very limited blood supply.
When a periapical lesion is allowed to persist for a length of time, such as two years, it frequently developes into a cyst, which is highly infected, and which must be removed by bone surgery, through the gum.
Most dentists that are performing the endodontic therapy will remind the patient of all the variables that can affect the outcome; and that long term infection free use of the tooth cannot be guaranteed.
For all these reasons, there is a need for a superior method of killing bacteria without toxins or antibiotics; because of the affect of antibiotics on the immune system of the body when taken in lengthy doses. Preferably the antibacterial device should be implantable in the tooth, for long term therapy. and prevention of reoccurrence of infection.
As early as 1933, a German dentist named S. Oppenheim placed two dissimilar metal wires, that were soldered together, into the root canal of infected teeth to produce "an electric current"; which had a helpful effect in the healing of the tooth. This is shown in his U.S. Pat. No. 2,009,112. At that time, he was not aware of the more recent developments in Ion Therapy; and he obviously did not have knowledge of the means for shaping an ion field, to guide the ion flow in the desired path; nor did this patent describe or anticipate the many specific requirements for successful endodontic therapy, that are presently used, and which are incorporated in the design of the new ion generator invention.
There are other patents that have been filed which recognize the value of electric current in therapy for diseased teeth and bone.
In 1979 Chlarenza and Weiss U.S. Pat. No. (4,175,565) an electroconductive dental implant that is imbedded in the jawbone of the subject which, with additional external equipment, is used to stimulate osteogenic activity in the bone structure adjacent to the dental implant. Although this patent does not immediately relate to root canal endodontics, it does recognize the use of electric current to increase the rate of normal healing and osteogenic activity.
Also, in 1979 Karostoff and Davidovitch, in their U.S. Pat. No. 4,153,060 , disclosed "apparatus for electrically stimulating bone growth and tooth movement in the mouths of mammals." By incorporating various external electrodes placed on gum surfaces in the mouth, they enhanced the repositioning of specified teeth in conjunction with normal orthopedic practices. In addition to an external constant current power supply and wires into the mouth, the apparatus adds additional cumbersome inhibitions to normal living; that would rule out the continuous or long term use of the system. This is in conflict with the long term continuous tension requirements of the orthodontic process. The system, by admission within the patent, was never used on a human patient.
In 1981 M. J. Nachman patented dental devices for "electrically stimulating a periodontium region within the mouth of a patient." (U.S. Pat No. 4,244,373) His devices are quite cumbersome when added to the mouth of the patient. The devices could not be applied to the patient during his normal course of work, eating etc.; and the patent requires an external power supply and circuitry for operation on a short term basis only.
In 1982 Jeffcoat and Wickham approached the problem of long term implantable bone growth stimulation: by enclosing a battery power supply and associated circuitry within a titanium bullet shaped case, with various external leads, etc., (U.S. Pat. No. 4,333,469) . Although practical for implantation in large difficult bone fractures, by invasive surgery, the approach has no value for treatment within the mouth. The patent does, however, bring out the difficulties in choice of materials, sealents, etc., for long term body implants.
The value of using electric current to enhance and quicken regrowth in bone and body tissue was further revealed in the 1984 U.S. Pat. No. 4,432,361; which describes a "continuously self-monitoring device for expediting the healing of bone or soft tissue fractures or defects." In addition to controlled power supplies, monitor circuits etc., which are external to the patient, the method includes the use of invasive surgery to insert metal electrodes into the flesh and bone ends at a bone fracture site. The method does not anticipate the use of a long term or permanent thermo-electric implant, such as described in the new invention.